Vehicle systems may include various vacuum consumption devices that are actuated using vacuum. These may include, for example, a brake booster and a purge canister. Vacuum used by these devices may be provided by a dedicated vacuum pump. In other embodiments, one or more aspirators (alternatively referred to as ejectors, venturi pumps, jet pumps, and eductors) may be coupled in the engine system that may harness engine airflow and use it to generate vacuum.
In yet another example embodiment shown by Bergbauer et al. in U.S. Pat. No. 8,261,716, a control bore is located in the wall of the intake such that when the throttle valve is at idle position, vacuum generated at the periphery of the throttle is used for a vacuum consumption device. Therein, the positioning of the throttle valve in an idle position provides a constriction at the throttle valve's periphery. The increasing flow of intake air through the constriction results in a Venturi effect that generates a partial vacuum. The control bore is sited so as to utilize the partial vacuum for a vacuum consumption device.
However, as recognized by the inventors herein, in the approaches described above, the vacuum generation potential of the throttle may be limited. For example, a single control bore at one location in the intake, as shown in U.S. Pat. No. 8,261,716, is utilized by the vacuum consumption device even though vacuum may be generated at the entire periphery of the throttle. To use vacuum generated at the entire periphery of the throttle, more control bores may be needed in the intake passage. However, fabricating these control bores may result in significant modifications to the design of the intake passage which can increase related expenses.
In the approaches that use one or more aspirators to generate vacuum, additional expenses may be incurred because of individual parts that form the aspirator including nozzles, mixing and diffusion sections, and check valves. Further, at idle or low load conditions, it may be difficult to control the total air flow rate into the intake manifold since the flow rate is a combination of leakage flow from the throttle and airflow from the aspirator. Typically, an aspirator shut off valve (ASOV) may be included along with the aspirator to control airflow but with added cost. Further, installing aspirators in the intake can lead to constraints on space availability as well as packaging issues.
As such, some approaches to address the above issues include providing a plurality of perforations around a circumference of a hollow intake throttle valve. The throttle valve may be adjusted to a more closed position to generate vacuum via intake airflow past the perforations on the circumference of the throttle valve. The generated vacuum is then applied to a vacuum consumption device fluidly coupled to the throttle valve via a hollow shaft.
The inventors herein have also identified potential issues with the above approach. As an example, the vacuum generation potential of the throttle is limited. As an example, the size of the perforations may be limited due to the width of the throttle valve, and therefore the vacuum generation potential of the throttle is limited. Thus, in order to increase the vacuum generated at the periphery of the throttle, the size of the perforations may need to be increased. However, increasing the size of the perforations may result in increases of the size and of the throttle which may result in significant modifications to the design of the intake passage which can increase related expenses.
The inventors herein have identified an approach to at least partly address the above issues. In one example approach, a throttle coupled in an intake conduit of an engine intake may comprise a throttle body, a slidable throttle valve included within the throttle body, the throttle valve comprising a hollow passage coupling a vacuum consumption device to an interior of the throttle body, and an inwardly projecting flange coupled within the throttle body. As an example, the throttle may be movable relative to the flange along a longitudinal axis of the throttle body between an open first position and a closed second position. An opening in the throttle body formed between the throttle valve and the flange may increase with increasing deflection of the throttle valve towards the open first position, away from the closed second position. Further, the throttle valve may include an aperture formed at an apex of the throttle valve by the hollow passage. A Venturi effect may be created at the apex of the throttle valve, and a magnitude of the Venturi effect may increase for decreases in a distance between the throttle valve and the flange. In this way, by moving the throttle valve to a more closed position, closer to the flange, vacuum may be generated at an apex of the throttle valve and used to draw air from a vacuum consumption device. In this way, an aspirator function may be integrated into the throttle.
As another example, a system may comprise an engine including an intake conduit, a throttle body included in the engine intake, the throttle body comprising, a throttle valve slidable along an axis substantially parallel to a direction of intake gas flow in the throttle body between an open first position and a closed second position, the throttle valve comprising a hollow passage fluidically coupling a vacuum consumption device to an interior of the throttle body, an inwardly projecting flow obstruction coupled within the throttle body, and a controller with computer-readable instruction stored in non-transitory memory for: in response to increases in vacuum demand, adjusting the throttle valve towards a more closed position to increase an amount of vacuum generated at an aperture of the throttle valve formed by the hollow passage at an inwardly extending tip of the throttle valve.
In yet another example, a method for an engine may comprise sliding a throttle valve within a throttle body of a throttle along an axis substantially parallel to a flow direction of intake gasses in the throttle, generating vacuum at a ridge of the throttle valve via intake air flowing past the ridge between the throttle valve and a throttle fixture of the throttle valve, and applying the generated vacuum to a vacuum consumption device fluidly coupled to the ridge of the throttle valve and flowing air from the vacuum consumption device into the throttle body.
In this way, a Venturi effect created between a throttle valve and a throttle fixture positioned in a throttle can be advantageously used to generate vacuum for a vacuum consumption device. The throttle valve may include a hollow interior passage that may be fluidically coupled to a vacuum consumption device for drawing air from the vacuum consumption device into the throttle. By adjusting the position, size, and/or shape of the throttle valve, the vacuum generation potential of the throttle valve may be increased. In addition, airflow into the intake manifold can be more accurately controlled by adjusting the distance between the throttle valve and the throttle fixture. Furthermore, since air received from the vacuum consumption device during vacuum application is received substantially at the throttle valve, airflow errors can be more accurately compensated for. By combining the functions of a throttle and an aspirator into a single throttle valve with a hollow interior passage, additional control valves, such as an ASOV, and parts may not be needed. By reducing the number and size of components required for vacuum generation, manufacturing expenses may be lowered and packaging issues may be averted.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.